Numerical Study on Evolution Mechanism of Cut Blasting and Cavity Formation Under Confining Pressure

Cut blasting is a key step in the drill and blast method. In underground engineering, confining pressure has a significant influence on the cut cavity formation process. In this study, the smoothed particle hydrodynamics-finite element method (SPH-FEM) considering confining pressure is used to describe the characteristics of the cut blasting process. The evolution mechanism of cut blasting and cavity formation under equibiaxial and anisotropic pressure is studied. The results show that the increase in confining pressure strengthens the rock clamping effect, and reduces the rock throwing, which is a nonlinear trend. The stress relief of the empty hole is obvious under high confining pressure, and the rock outside the empty hole is more likely to be thrown than that outside the cut hole. Under anisotropic pressure, the throwing pattern of rock fragments gradually shifts toward the direction of high confining pressure, while the rock accumulates in the direction of low confining pressure. The cut effect in a certain direction is dominated by the perpendicular confining pressure, but the increase in the horizontal confining pressure also has an inhibitory effect. Finally, suggestions for adjusting the hole distance, empty hole parameters, bottom cavity charge, and delay time are proposed and discussed.